1. Field of the Invention
The invention generally relates to light sources capable of mixing light colors using a plurality of colored light-emitting elements.
2. Description of Related Art
LEDs are increasingly employed for lighting purposes for instance in vehicles and building interiors, e.g. in aircraft cabins. LEDs are particularly suitable in these fields because of their low energy consumption and low operating voltage.
For example, WO 2010/013181 A1 discloses an optical element with a light transmitting region having a constant cross section over the entire length thereof. Adjacent to this light transmitting region in the direction of the light beams is a light collimating region that has a cross section increasing in the propagation direction of light. The end of the light collimating region is defined by an inclined reflector. The light reflected at this reflector exits the optical element substantially perpendicularly to the propagation direction of the light in the light transmitting region. The light collimating region may have various geometric shapes.
DE 10 2012 022 716 A1 discloses a method for injecting light into and mixing in a light guide. The light is injected into the light guide substantially perpendicularly to the latter, impinges onto an inclined reflector and is reflected by the latter into the light guide. Mixing of the light is accomplished by total internal reflection of the light beams at the inner walls of the light guide.
The described prior art light mixers exhibit a high degree of symmetry which is quite advantageous for a pure light mixer.
However, if the optical element has a deflection function, the symmetrical configuration proves to be disadvantageous for a most efficient exploitation of the light in additional downstream optical systems.